Molding machine



June 29, 1948. w DINZL 2,444,339

MOLDING MACHINE Filed May 24, 1944 5 Sheets-Sheet 1 INVENTOR BY r TTORNEY June 29, 1948.

R. W. DlNZL MOLDING MACHINE Filed may 24",

5 sheets-sheet 2 ATTORNE INVE R. W. DINZL MOLDING MACHINE June 29, 1948.

5 Sheets-Sheet 3 Filed May 24, 1944 w kw lN-VENTOR d. TTORN EY;

June 29, 1948. w DlNZL 2,444,339

' MOLDING MACHINE Filed May 24, '1944 5 Sheets-Sheet 4 June 29, 1948. R. w. DlNZL I MOLDING MACHINE Filed May 24, 1944 5 Sheets-Sheet 5 Q \w a A Q R Q m0 a a & m N x Q Q Q w i q R k QB lllllll J m QR m m u #i" .QM. W mw mm g m ww r J M N Hm ww m BI I Patented June 29, 1948 2,444,339 MOLDING MACHINE Richard w. .Dinzl, Westfield, N. 1.. assigncr to The Watson-Stillman 00., Roselle, N. J., a corporation of New Jersey 7 Application May 24, 1944, Serial No. 537,077

This invention relates to molding machines.

An object of this invention is the provision in an automatic molding machine of apparatus for checking the conditionof the die members of the machine after completion of a molding cycle in combination with means, for interrupting the operation of the machine in the event that either of the die members retain any residue of molding material which might interfere with .the proper operation of the machine.

A molding machine embodying the. invention includes a vertically movable ram carrying a die member for movement into and out of engagement with a stationary die member. The ma chine also isprovided with. a slide mcvable into and. out ofthe path of the movable die member and is equipped with feeler means movable there'- in in the direction of travel of the movable die member. Thefeeler means are biased away from the stationary die member. Means are provided for causing the ram to descend under low pressure preferably less than. its own, weight, to en.-,

gage the feeler means and depress the'same into the diecavities. In the event that no residue has been left on or in the die members from the previous molding cycle, the ram descendsa predetermined distance and operates the control means of the machine to cause the machine to run through a molding cycle. In the event that either of the molding members. retains any residue the ram is prevented from descending'the predetermined extent whereupon operation of the Fig. 3 is an enlarged section on the line 33 of Fig. 2;

Fig. 4 is a hydraulic diagram, and

Fig. 5 is a Wiring diagram. "Inthe frame 5 is provided a bed 6 on which is mounted a die block 1 having one or more recesses 8. 5" for movement toward and away from the bed A ram 9 is mounted in the frame 16 Claims. (c1; 18-16) 8 and carries a die block l0 having projections H suitably shaped to enter the recesses 8 and press into desired shape charges of thermoplastic material contained in the recesses.

The ram 9 terminates at its upper end in a piston 13 received withina cylinder l4 carried by the frame 5. The piston I3 is caused to reciprocate in the cylinder [4 by means of oil or other suitable liquid supplied to and removed from the cylinder through the conduits I5 and IS. The frame carries a tank I! in which oil is con-- tained and a motor-driven pump I8 is provided for supplying the oil under pressure. The tank I1 encloses the major portion of the cylinder l4 and a hydraulic system (Fig. 4) including the conduits l5 and I6 for supplying oil to and withdrawing oil from the cylinder H as well as electrically-operated means for controlling the flow of oil in the hydraulic system.

' A slide I9 is mounted on horizontal guides for reciprocation into and out of the path of the ram 9. The slide is is attached by a rod 20 to a piston 2| arranged in a horizontal cylinder 22 vented at its left end. The right end of the cylinder 22 is connected to a three-way valve 23 having a port communicating through a conduit 24 with a source of compressed air and another port communicating with atmosphere. spring 25 biases the valve 23 into the position in which the cylinder 22 is in communication with the atmosphere and ,there is provided a solenoid 26, which, when energized, operates the valve to disconnect the cylinder 22 from atmosphere and connect it to the conduit 24.

The slide I9 supports a multiplicity of vertically reciprocable feelers 27 which are biased upwardly by springs 28. The feelers 21 are for use in stopping theoperation of the machine in the event that, after completion of a molding operation, a die cavity 8 or a projection ll retains any thermoplastic material.

In the operation of the press and with the ram 9 elevated after completion of a molding operation, the solenoid 26 is energized to operate the valve 23 to connect the cylinder 22 to the conduit 24, whereupon the slide l9is moved from the positicn shown in Fig. 3-into a position in which the feelers 21 directly underlie'the projections I I.

Then, by an arrangement subsequently tobe described, the ram 9 is caused to move downwardly slowly by gravity. If the projections I I are clean and there is no material in any recess 8, the ram descends to a predetermined extent, pushes the feelers 21 downwardly into the recesses 8 against the action of the springs 28. In the event that the ram moves downwardly the predetermined extent above mentioned, the control mechanism (subsequently to be described) is so aiTected that the feeler slide I9 is returned to its original position after the return of ram to its top position and the machine follows through another molding cycle. However, in the event that because of some obstruction either on a projection II orqin. a recess 8,. the ram 9 is prevented from descending the above-mentioned predetermined extent, then the control mechanism is afiected in such a manner that operation of the machine is interrupted-;-

A feed slide 3t is arranged iorv reciprocation;

into and out of the path of theramf 9 by a hydraulic motor embodying a cylinder 3I and a piston 32 as shown and deseribedin the ,U. S. patent to Farley, No. 2,256,081: Oil is supplied" to and withdrawn from the hydraulic motorby; conduits 33 and 54. The right end of the feed slide this engagedby theleft end of; the feeler slide Hi on leftwardmovement of the latter to locatev it properly under the ram. The feeler slide 59 is moved out of the path, of the ram by rightward movementof the feed slide into the. path of the, ram 9, the,valye,23, then being Assume that the, machine; has completed a,

molding cycle and the ram isat the top of its,- stroke with the. slide I9 'inrthe position shown in Fig. 3. In this positi0n,,the limit switch 39- is open by reason of disengagement therefrom of the member 4| and the limitswitch 38-is closedby thevmember 4!) to complete acircuit toenergizethe solenoid 26 to operate the. valve 23,to

cause compressed air to be supplied to the right end of the cylinder 22 to effect leftward movement of the piston 2|..to locatethe slide It withthe feelers 21 underlying. the projections I I.

Inward movement of the,slide,I9 causes operationof the limitswitches-35, 35 and}? toaffeet the control mechanism in suchrnanner that the, ram descends under very light pressure. On downward movement, the member 49 releases switch 38 which opens. automatically and the.

membertl releasesoriails to release the limit switch 39 to closed condition depending upon whether the ram descends to a predetermined extent or fails-to descend to said predetermined extent. If the ram descends to the predetermined extent so that the switch 39,is, .closed,the ram dislifted and the solenoid 26 is de-energized thereby effectingoperation of valve 23 in suchmannerthat the left end of the cylinder 22 is opened to, atmosphere. Thereupon, the feeder slide tll is operated to charge the recesses 8 with;

molding material as described in said Farley Patent No. 2,256,081, after which the machine proceeds through a molding cycle. Should the ram fail to descend to the predetermined extent, the limit switch 39 is not closed and the operation of the machine is stopped. The machine will remain in its stopped condition until operation is re-established by the operator of the machine.

The operation of the ram 9 is effected by means of the hydraulic system diagrammatically illustrated in Fig. 4 under the control of the electric systemschematically illustrated in Fig. 5. The pump I 8 has its outlet connected through a conduit 43 to the inlet of a tandem open-center four-way valve 44 equipped with operating solenoids 45 and 4B and having an outlet 41 communicating with the interior of the tank H. The outlet of thepump I8 also communicates through the conduit 48 with the inlet of a four- Way valve 49 equipped with an operating solenoid 50 and resetting spring 5| and having an outlet 52 communicating with the interior of the tank II.-

One port 53 of the four-way valve 44 communicates with the conduit I5 leading to the upper end of the cylinder I4 through aprefill valve while another port 54 communicates with the conduit I6 leading to the lower end of the cylinder I4. The prefill valve comprises a cylindrical housing havinga bore 56 through it of two difierent diameters. The topend of the prefillvalve 55' isconnected to the conduit I5 while the other end of the valve engages the v top of the cylinder I4 in which is provided a passage 51 leadingto the interior of the cylinder, the passage 5! communicating with but being of smaller cross section than, the lower end of the bore 56. In the bore 56 is arranged a twodiameter piston 58 having a central passageway 59 of less cross-section than the passage 51. One

or more passageways 60 lead from the lower portion of the bore 53 .into the tank. When the piston 5811s depressed, the port5'l is partially closed and the cylinder I4 is in communication only with the. conduit I5 through-the passageway 59; When the piston 58 is elevated, the port 5'! is fully open and the cylinder I4 is additionally in communication with the tank I'I through the p ssa ewa 9.

portion of the bore 56.

One port of the valve 49 communicates with the conduit 33 leading to one end of thecylinder 3|,whiletheother port communicateswith the conduit 34 leading to the other end of the cylinder. A conduit 62 leads from the conduit I6 throughaneedle valve 63 to the inlet of avalve B4 equipped with an operating solenoid 65yand resetting spring 66 and an outlet communicating withrthe, tank II.

The valve 44 is of such design t at'withboth solenoids 45, and 46 dc-energized, both ports 53' conduit I5 to the cylinder I4 and fiowsfrom thev cylinder I4 through the conduit I6 .tothetank by A conduit 6| leads, from, the. conduit I6to the lower end 'of the larger diameter to establish communication l "Movement of the slide I!) shown in Fig, 3 into the path of the ram 9 is acpressed air (not shown). ithejdie blocks after completion of a molding The arrangement of the valve 49 is that with the solenoid 53 de-energized; the-sprin maintains the valve in apositioninwhichoil flows through the conduit 34 to the cylinder 3| and flows from the cylinderill through the conduit 33to the tank through the outlet 52. Energization of .the solenoid 53 operates, t e valve 49 against the action of the spring 5| into a position inwhich oil flows through the conduit 33 tothe cylinder 3i and flows from the cylinder 3] t rou h the conduit 34 'to the tank by way of the outlet 52. The arrangement of the valve 64 is such that when the solenoid 65 is de-energized, the springfifi holds the valve in a position in whichcommunication is interrupted between the conduit 62 and the tank I! but when the solenoid 35 is energized, the valve is operated between the conduit 32 andthetank H, i v n from the position complished by energization of the solenoid 26 to cause compressed air to flow into the right end of the cylinder 22. 'Upon de-energizatio'n of the solenoid 25, the valve 23 is returned by the spring -25into position to open the right end of the cylinder '22 to atmosphere. Upon energization of=the solenoid 50, the valve 49 is operatedto direct oil flow to and from the cylinder 3| to cause'movement of the feeder slide 30 into the path of'the ram 9 and concomitant return 01 the feeder slide 19 to itsFig. 3 position. De-energization of the solenoid 50 results in operation of the valve 43 to direct oil flow to and from the cyl- -inder 3| to cause movement of the feeder slide 3li outof the path of the ram 9. gization of the solenoid'fi5 only, the ram9 is Upon enerlifted and held lifted until the solenoid is deenergized. Upon energization of the solenoid 46 only the ram is moved downwardly and held down until after"de-energization of the solenoid 43. Energization of thesolenoid 35 results in operation of the' valve 64 to by-pass oil from the cylinder-li around the valve 44 through thevalves '33and34 to the tank l7.

- Downward movement of the ram 9 for engagement of the projections" H with the feelers 21 -is effected by energization of the solenoid 65 with both solenoids 4'5 and 43 de-energized and both ports 53 and 54 of the valve 44 blocked. Energization of the solenoid 35 causes operation of the 'valve 63 to put the conduit 62 in communication withthe tank l1 thereby allowing liquid to flow throughthe' needle valve 63. The weight of the ram exerts pressure on the oil in the cylinder It below the piston l3 tending to cause flow through the conduit 62 and the rate of flow is determined-by the needle valve 63.' This pressure is communicated through the conduit (if to the under surface of the enlarged portion of the pistion. of the cylinder and very slight pressure is applied to the feelers 21. i

A pipe El is connected to a source of com- During' opening of 3 operation, a stream of air is supplied through the pipe'for the purpose of stripping the finished it is under the ram 9.

articles from the projections H as well as blowing out the cavities 8. t

Energization of the solenoids is efiected by the electrical system of Flg. 5 in which 38 is one conductor and 69 is the other conductor of an alternating current supply. The conductor 38 is connected to the conductor 69 through the normally-open or self-opening limit switch 38 and the coil of arelay H. The switch 38 is closed by the, ram in its raised position. The conductor 68 is also connected through the normallyopen or self-opening limit switch 39, the normally-open or self-opening limit switch 35, a

pair of normally-closed or self-closing contacts 12a constituting part of a timer (2 laterto be described and the coil of a relay 13. The switch 39 is released by the member for closing upon a predetermined downward movement of the ram andthe switch 35 is closed by the slide i9 when In addition, the conductor 68 is connected to the conductor 39 through a pair of normally closed or self-closing contacts 13b of the relay 13, a pair of normallyopen or self-opening contacts Ha, of the relay through the contacts 13b, the normally-open or self-opening contacts 31?) of the limit switch 3? and the solenoid 6B. The conductor 63 is additionally connected to the conductor 39 through the contacts 31a, a pair of normally-open or self-opening contacts Ma of a relay M (subsequently to be described) and the solenoid 53. The conductor 68 is also connected to the'conductor 69 through said contacts 31a, a pair of normally-closed or self-closing contacts 'Hlb of the relay 14, a pair of normally-open or selfopening contacts 15a of a relay l5 (subsequently to be described), the normally-opener selfopening limit switch 42, the normally-open or self-opening limit switch 36 and solenoid 43. In addition, the conductor 68 is connected through the normally-closed or self-closing contacts 37a of the limit switch 31, a pair of normally-closed or self-closing contacts 15b of a relay 15 (subsequently to be described) and the solenoid 45 to the conductor 69. A pair of normally-open or self-opening contacts 13a of the relay 13 are shunted around the contacts 31a.

A conductor 16 leads frombetween the switch 35 and contacts 12a through a pair of normallyopen or self-opening contacts lib of the relay H, a pair of normally-open or self-opening contacts 11a controlled by a timer 71, the limit switch 42, a pair of normally-open or self-opening contacts 18a controlled by a timer l8 and a solenoid 19 for operating a valve (not shown) controlling flow of air through the pipe 61. A pair of normally-open or self-opening contacts of the relay '13 ar arranged in a shunt circult around the switches 39 and 35, The timer 11 is connected to the conductor 16 between the tacts 18b controlled by the time 18. The timer 18 is connected to the conductor 76 between the contacts 18a and the switch 42 and to the con- 9 through the tank I! to the under face of the larger portion of the valve 58 to lift it and open the passage 60, thereby permitting flow of oil from the tank into the cylinder or keep full that portion of the cylinder above the ram I3. When the ram reaches its working stroke, further downward movement is effected by the pressure of the oil in the cylinder above .the ram and the rate of flow through the conduit 16 drops with consequent drop in the pressure supplied to the prefill valve through the conduit 6| resulting in descent of the piston 58 into position to close the passage 80 and limit flow of oil to the cylinder M to that supplied from the pump I8 through the conduit I5.

After the timer 18 times out it closes the contacts 18a and opens the contacts 18b thereby deenergizing the relay 15 to close the contacts 15b and open the contacts 15a. Thereupon current flows from the conductor 68 through the contacts 31a and 14b and 15b to the solenoid 45 whereupon the valve 44 is set to cause the ram to be lifted. Closure of the contacts 18a also causes current flow through the timer l2 and the solenoid 19 to direct a stream of air through the pipe 67 against the projections H to remove the molded article therefrom during upward movement of the ram. When the blower timer 12 times out, the contacts 12a are opened, thus breaking the circuit through the relay I3 whereupon the contacts 13a and 130 open and the contacts 1317 close, thereby again energizing the solenoid 26 to condition the machine for another molding cycle. The timing out or the blower timer 12 allows all the timers to reset.

I claim:

1. In a molding machine, a stationary base, a ram vertically movable toward and away from said base, hydraulic means for operating said ram, a slide movable into and out of the path of said ram, feeler means supported by said slide for reciprocation parallel to the path of said ram. said feeler means being biased away from said base and engageable by said ram for movement thereof toward said base when said slide is in the path of said ram, and control mecharender said hydraulic means inoperative and release said ram for movement toward said base at controlled velocity under the influence of gravity and means responsive to movement of the ram a predetermined distance toward the base for rendering said hydraulic means again operative.

2. In a molding machine, a stationary base, a ram vertically movable toward and away from said base, hydraulic means for operating said ram, a slide movable into and out of the path of said ram, a rod supported by said slide for reciprocation parallel to the path of said ram, said rod being biased away from said base and engageable by said ram to move it toward said base when said slide is in the path of said ram, and mechanism for controlling said hydraulic means, said mechanism including means responsive to movement of said ram to its uppermost position to render said hydraulic means inoperative and release said ram for movement toward said base at controlled velocity under the influence of gravity and means responsive to movement oi? said ram a predetermined distance toward said base to render said hydraulic means again operative. a

3. In a molding machine, a stationary base, a ram movable toward and away from said base, a vertical hydraulic motor operatively connected to said ram, a source of fluid under pressure, valve means for controlling fluid flow from said source to said motor and from said motor and also having provision for preventing fluid flow into said valve means from said motor, a bleed for withdrawing fluid from the bottom end of said motor, a valve normally closing said bleed, a slide movable into and out of the path of said ram, means responsive to movement of the slide into the path of the ram to open said bleed valve and condition said valve means for preventing fluid flow thereinto, means responsive to a predetermined extent of movement of said ram to effect closing of said bleed valve and conditioning of said valve means to permit fluid flow thereinto, and means responsive to the pressure in the lower portion of said motor for admitting fluid to the top of said motor. i l T 4. In a molding machine, a vertical cylinder, a piston reciprocable therein, a ram connected to said piston, a tank communicating with the top of said cylinder, a conduit leading from the bottom of said cylinder, a source of fluid under pressure, valve means for controlling fluid flow from said source to said cylinder and from said cylinder to said tank and having provision for preventing flow into said valve means from said cylinder, a

bleed for withdrawing fluid from the bottom end of said cylinder, a normally closed valve in said bleed, a slidemovable into the path of said ram to open said bleed valve and condition said valve means to prevent fluid flow thereinto, means responsive to a predetermined extent of downward movement of said ram to effect closing-of said bleed valve and conditioning of said valve means to permit fluid flow thereinto, and a-valve responsive to the pressure in the lower portion of said cylinder for controlling flow from said tank into said cylinder. e i

5. In a moldingmachine, a stationary base a ram vertically movable toward and away from said base, a vertical cylinder, a piston reciprocable in said cylinder and connected to said ram,

a source of fluid under pressure, valve means for controlling fluid flow from said source to said cylinderand from said cylinder and having provision for preventing flow into said valve means from said cylinder, a valve-controlled vent from the lower end of said cylinder, a slide movable into and out of the path ofthe ram, feeler means supported by said slide for reciprocation parallel to the path of said ram, said feeler means being biased away from said base and engageable by said ram for movement thereof toward said base when said slide is in the path of said ram, control means for said valve means, means for opening said vent with said slide under said ram and setting said valve means in. position to prevent flow therethrough from said cylinder, and means responsive to the movement of said ram a predetermined distance toward said base for resetting said valve means to supplyfluid again to said 7. In a molding machine, a ram vertically movable between a first position and a second position, a vertical cylinder, a piston reciprocable in said cylinder and connected to said ram, a source of fluid ,under pressure,- -valve' means forcontrolling fluid flow irom said-source to said-cylinder and from saidcylin'der and=having provision for preventing flow into said'valvemeans from said cylinder, a valve controlledv'ent from the lower end of said cylinder, a slide movableinto and-out of the'path of the' ram, feeler means supported by said slide for reciprocation parallel to the path of said ram, said feeler means being biased toward said ram and e'ngageable by said ram for movement thereby when said slide is in the path of said'ram, means responsiveto movement of saidraminto its first position formov ing saidslide into the path of said ramymeans sponsive to the return of said ram to its first position for retracting saidslide.

8. In amolding'mach-ine according to claim 7, means responsive to pressure in the lower portion'of said cylinder-for admitting fluid into the top of said cylinder.

9. In a molding machine, a ram vertically movable between a first'position and a second position, a vertical hydraulic motor operatively connected to said ram, a source of fluid under pressure, valve means for controlling fluid flow ,from' said source to said motor and from said motor v and also having provision for preventing fluid flow into said valve means from said motor, a

slide movable into and out of the path of: said ram, feeler means supported by said slide for reciprocationparallel to the'path 'of said ram; saidfeeler means being biased toward said ram and engageable' by said ram for movement thereby'when'said slide is in the path of said ram,

means responsive to movement of said ram into" its first position for moving said slide into the path of said ram; and means responsiveto move-' ment of said slide into such position to releasefluid from the lower endof said motor and'set saidvalve means to prevent flow'ther'einto from' sal'dmotor;

10. 'In a molding machine according to claim 9, additional'means responsiveto pressure in the lower portion of said motor for admitting fluid to the top portion thereof;

11. In a molding machine,=a vertical cylinder,

a piston reciprocable therein, a ram connected to said piston, a tank communicating with the top" of said cylinder, a conduit leading from the bottom of said cylinder. a first valve controlling flow through said conduit,a second valve responsive to pressure in the *lowerportion of said cylinder forcontrolling communication-"between said tank and the top of said cylinder; a source" of fluidunder pressurejvalve means for'controlling fiuid flow fromsaid source to said cylinder and from" said cylinder to said tank and having provision for preventing flow into said'valve means from said cylinder, a bleed for withdrawing fluid from the bottom end of said cylinder, a normally? closed valve in said bleed, a slide movable into and out of the path of the ram; feeler means sup-uportedby said-slide for reciprocation parallel to :11

the path of said ram,--'said 'feelermeans being biased toward said ram, andengageableby said ram for movement thereby when said slide' is inf:

the path of said ram; means responsive'to'move mentof said ram into itsupper-position for'mova ing' "said slide into the" path'-of' "said ramgi'means responsivei tousuclrzmoyement zof said slide 'for;

opening iisaidi :ble'ed valve and conditioning a said 1 valve meanssto preventtfiowzthereinto from said cylinder-'xmeans responsive: to the movement of 'saidi-ram more. than. a predetermined downward distancesto effectxciosingof said'bleed valve and conditioning-10f said valve means to permit'fiow tnereintoi afrom "said cylinder;

and i additional tv means responsiveitothefreturn: of s'aid-ramrto its 12:1In -5a. moldingxmachine. according to claim llpadditi'onal means responsive to pressure in theiloweii POI'tiGlfLiOf said :cylindenfor' admitting fiuid intor the top fof said cylinder;

13. In a molding machine, a stationary base, a ramfi -yerticallymoyable: toward and away from said baseg'ia vertical :hydraulic motor connected to saidxramutocfiect reciprocation thereof, a

hydraulic: fluid reservoir; a pumpior withdraw- .ingt fiuid rfroin said reservoir; connections for flowings-hydraulicfiuid to and 'from said motor includingra fourewayzvvalve operative to -selectively conne'ctithe-tends of said; hydraulic motor 1 to said. pumptandzreservoir or to'interrupt. com- 1 imunication' a between" said motor and both said-*- pumpandre'servoir, a self-closing vent from the lower-end x of said motorpa slide movable into and toutsofthe path of said ram,-feeler means supported-'bysaid slide for reciprocation parallel to the pathx'of saidram; said'feeler meansbeingbiased" awawfromsaid base and-engageable bysaid :ram for movementi therebytoward said base when sa-id-slideiis in the-pathoi said-ram, means responsive to'movementof said ram into its up,- Hpermost position to reciprocate said slide intothepath of said ram and set said four-way valverto interruptcommunication between said motortand both said: pumpirand said reservoir;-means operated by movement 'of' said :slide into the path' of said-.ram-to open said=ven-t, means responsive to downward =movement: of theramover-- a predetel-mined. distance to set said valveto supplyhydraulic :fluidto the lower I end of said 3 motor andseffect-closing of said? vent.. I

H-JIn-amolding machine, .a stationary. base; a

ram,.yertically-.-movable toward. and away from said base, a vertical/hydraulic motor connected to said ram to effect reciprocation thereof, a hydrauliorfiuidi-reservoir,va pump for withdrawing l'fiuid'from said reservoir, connections for flowing hydraulic fiuidto and from said .motor. including 7 a fou'rrway-valveloperativevto selectively connect the ends of said hydraulic motorto said pump and-.reservoin or to interrupt communication betweenasaida motor. andoboth said pump and reservoir, a self-closing vent from the lower end of said.- motor, a slide movable into and out of the-pathHof said ram a rod-supportedby said slideafor.reciprocation.parallel to the pathof baseaandengageable .by saidlram for movement thereby toward said base when said slideeis in.

the pathof said ram, meansresponsive to movementor said ram.into its uppermost position to reciprocate -.said;.slide intothe path of said ram andlset,saidhfour-wayuvalve to interrupt communication between said 'motor and .both said pump-sand saidreservoir, means. operated. .by

moVemeI-itofisaid slide into the path of said ram toopen said'vent, means responsive to downward movement of the ram overapredetermined distanceatoqset. said valve to supply hydraulic fluid :to the'xlower end -.of, said motor .and.,effect.

closingof said-vents" 15. In a molding machine according to claim.-."

saidiram said -rodflbeing biased awayflfrom said 7 E35 14 13, means responsive to the pressure at the lower a end of said motor for admitting hydraulic fluid UNITED DTATES PATENTS at the top end of said motor. umber Name Date 16. In a molding machine according to claim ,613,56 Grattan Jan. 4, 1927 14, means responsive to the pressure at the lower 5 1,870,500 Ernst Aug. 9, 1932 end of said motor for admitting hydraulic fluid 84,060 MacMillin Oct. 25, 932 at the top end of said motor. 2,148,543 Dinzl Feb. 28, 1939 RICHARD W. DINZL. 71, 9 Strauss Mar. 13, 1945 2,257,732 Clark Oct. 7, 1941 REFERENCES ED 19 2,276,016 Brantly Mar, 10, 1942 The following references are of record in the file of this patent:

Certificate of Correction Patent No. 2,444,339. 7 June 29, 1948. RICHARD W. DINZL It is hereby certified that error appears in the printed specification of the above umbered patent requiring correction as follows: Column 4, line 71, after the word d diiduitj" insert 61 and flows from the cylinder 14 through the conduit; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 2nd day of November, A. D. 1948.

[SEAL] THOMAS F. MURPHY,

Assistant Q'ommz'ssz'oner of Patents. 

